Enclave and exclave
In political geography
Political geography
Political geography is the field of human geography that is concerned with the study of both the spatially uneven outcomes of political processes and the ways in which political processes are themselves affected by spatial structures...

, an enclave is a territory whose geographical boundaries lie entirely within the boundaries of another territory.

An exclave, on the other hand, is a territory legally or politically attached to another territory with which it is not physically contiguous.

These are two distinct concepts, although many entities fit both definitions.
In Fig. 1 at right, C is an exclave of B, and is also an enclave within A.